1. Field of the Invention
The present invention relates to a method and apparatus for providing a multi-channel sensing and switching device.
2. Brief Description of Related Art
There are many known method and apparatus for providing multi-channel sensing and switching.
For example, U.S. Pat. No. 6,998,807, owned by the assignee of the instant patent application, discloses an active sensing and switching device having a controller that senses a signal indicating a sensed value of electrical current to a load, determines a nominal value for the electrical current to the load based on monitoring over a period of time, and disconnects the load from a power source based on the signal. The disconnection can be made after a waiting period. The controller can also receive signals indicating sensed values of electrical current to a plurality of respective loads. However, among other things, the '807 patent does not disclose controlling different load types using different load type control signals, or using a time/current magnitude weighted algorithm, or using a combination of sensed current and voltage, or using a centralized controller for centralized real-time control. However, the technique disclosed in the '807 can handle only one channel at a time and has no branch circuit protection, and it is also not field programmable.
Other known techniques include the following:
Patent Application Publication No. 2007/0086135 discloses a fault circuit indicator having an adjustable trip circuit for producing a trip output using a technique based on an adjustable trip level that depends on the passage of time and at least one fault indication curve.
U.S. Pat. No. 4,937,757 discloses circuit interrupters having selectable trip parameters using a technique based on a logarithmic interpolation algorithm for interpolating between fixed data points stored in memory means corresponding to thermal and magnetic interruption devices to generate a continuous representation of a calculated time delay. An EEPROM provides data. The timing is based on current levels and the trip curves are taught for different levels of current.
Patent and publication nos. U.S. Pat. Nos. 6,545,849, 7,016,174 and 2003/0107860 are similar to the above '757 patent where current and threshold valves are detected to control tripping. A multi-algorithmic approach is employed. In particular, the '849 patent discloses an instantaneous fault technique based on a comparison of an absolute value of a present current value and a first current threshold, and of a multiple peak sum and a second current threshold. The '174 patent and '860 publication contain similar features.
Moreover, other know techniques include a circuit breaker system using a technique based on historical memory information associated with individual breakers; a circuit breaker system using a technique based on a comparison of power line data and historical power line data; an electronic trip unit based on a repetitive sampling, comparison and incrementing technique; a distributed monitoring and protection system using a technique based on a comparison of measured electrical parameters, e.g., from different current nodes at different potentials, or from different branches, measured by two monitoring units; an electronic trip unit using a technique based on a comparison of a rate of rise of electrical characteristics to detect a spike and a withholding of a trip signal when the rate is greater than a limit value selected by a switch; a panel board configured for distributing electricity from a power source using a technique based on controlling main circuit breakers and branch circuit breakers; a power supply device having an AC power supply, rectifier and capacitor combination using a technique, e.g., based on controlling a connection depending if a voltage applied across the capacitor exceeds a predetermined PFC voltage limit; a control system for a power supply protector controllable through an IP address; a power control using a technique based on zero crossing logic; a system for controlling power to a plurality of loads, one being a primary power source, and at least one being a back-up power source, using a technique based on categorizing delayable and non-delayable loads and allocating power based on the categorization.
Moreover, in the prior art circuit breaker protection for certain load types, such as pumps on boats as well as other particular applications, is known to include the use of MOSFET devices in combination with in-line fuses to protect the load types from being damaged by, e.g., high current. In operation, such MOSFET devices that are able to handle such high currents, e.g. 30 Amps, are typically expensive devices, costing in the range of as much as, e.g., $3-5 per device (at the time of filing the present invention). In practice, when such MOSFET devices burn out, the MOSFET and in-line fuse typically have to be repaired, which usually results in a service cost and/or charge to the owner of the boat or other suitable application that can e expensive. In view of this, there is a need in the art for improved circuit breaker protection for these types of applications.